Quasi-sparse optical illumination

ABSTRACT

In described examples, a DMD includes micromirrors. A first light source generates a first beam profile illuminating a first set of micromirrors of the DMD. A second light source generates a second beam profile illuminating a second set of micromirrors of the DMD. The first and second beam profiles partially overlap on at least some micromirrors of the DMD. The first light source is source-modulated independently of the second light source for adjusting power and brightness in response to a sensed driving condition. The micromirrors of the DMD are modulated in response to the sensed driving condition.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/659,600 filed Jul. 25, 2017, which claims priority to U.S.Provisional Patent Application Ser. No. 62/366,922 filed Jul. 26, 2016,the entireties of which are incorporated herein by reference.

BACKGROUND

In some lighting systems, light for projection is sourced by emission oflight from a lamp or laser. The emitted light is often reflected andfocused upon for projection for illuminating a specific area. Theemitted light can have a white-correlated (“white”) color temperature,so a white light is projected for illumination, such as illumination ofa dark road when driving a vehicle. Some vehicles mechanically couplethe steering wheel to a headlight assembly, so the projected light isredirected from straight ahead (e.g., perpendicular the vehicle's front)to either a left or right orientation, according to a direction in whichthe vehicle is turning. However, such systems are often cumbersome andrequire sufficient area to pivot an entire headlight assembly. Also,additional calibration procedures and/or operational power can be neededfor proper operation of the steerable headlight assemblies.

SUMMARY

In described examples, a DMD includes micromirrors. A first light sourcegenerates a first beam profile illuminating a first set of micromirrorsof the DMD. A second light source generates a second beam profileilluminating a second set of micromirrors of the DMD. The first andsecond beam profiles partially overlap on at least some micromirrors ofthe DMD. The first light source is source-modulated independently of thesecond light source for adjusting power and brightness in response to asensed driving condition. The micromirrors of the DMD are modulated inresponse to the sensed driving condition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an orthographic view of a headlight assembly for beam steeringwith quasi-sparse illumination.

FIG. 2A is a top view of a headlight assembly for beam steering withquasi-sparse illumination.

FIG. 2B is a side view of a headlight assembly for beam steering withquasi-sparse illumination.

FIG. 3 is a group of graphs showing irradiance plots of DMD opticallyactive surfaces for source-modulated beam steering with quasi-sparseillumination.

FIG. 4A is a diagram of an inner margin of a first projection aperture.

FIG. 4B is a diagram of an inner margin of a second projection aperture.

FIG. 4C is a diagram of an inner margin of an illumination aperture.

FIG. 4D is a diagram of an illumination and/or projection aperture.

FIG. 5A is a diagram of a system for illuminating a DMD withnon-overlapping beam generation from multiple light sources.

FIG. 5B is a diagram of a system for illuminating a DMD with partiallyoverlapping beam generation from multiple light sources.

FIG. 5C is a diagram of a system for illuminating a DMD with completelyoverlapping beam generation from multiple light sources.

FIG. 6 is a side view of a headlight assembly for source-modulated beamsteering with quasi-sparse illumination from same-side light sources.

FIG. 7 is a diagram of multiple collection lenses for independentlysituated and oriented light sources, for partially overlapping beamgeneration for illuminating a DMD.

FIG. 8 is a diagram of a single collection lens for independentlysituated and oriented light sources, for partially overlapping beamgeneration for illuminating a DMD.

FIG. 9 is a diagram of a single collection lens for planar lightsources, for partially overlapping beam generation for illuminating aDMD.

FIG. 10 is a side view of a headlight assembly for beam steering withquasi-sparse illumination from direct and indirect light sources.

FIG. 11 is a block diagram of a vehicle system for source-modulated beamsteering.

FIG. 12A is a view (from a vehicle) of beam-steering when the vehicle isdriving straight ahead.

FIG. 12B is a view (from a vehicle) of beam-steering when the vehicle ismaking a shallow turn.

FIG. 12C is a view (from a vehicle) of beam-steering when the vehicle ismaking a sharper turn.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

In this description: (a) the term “portion” can include an entireportion or a portion that is less than the entire portion; (b) the term“package” can include a substrate or a sealed container, such as die,wafers or micromechanical devices in a local environment that is sealedfrom an outside environment; (c) the term “sparse” can include partiallyilluminated areas of a pupil (e.g., irradiated area); and (d) the term“optical elements” can include lenses, mirrors or both.

In many illumination systems, a locally generated beam of light isparabolically reflected and focused through a lens, so a specific areais illuminated. In many vehicles, a headlight assembly includes a lamp,large-scale parabolic reflectors and lenses. The headlight assembly islocally pivoted (e.g., with respect to a vehicle chassis) in response toa controlling movement of the steering wheel of the vehicle. Forexample, mechanical linkages and/or headlight assembly motors can pivotthe headlight assembly in response to normal rotational movement of thesteering wheel, so the beam of light can be directed with a greaterdegree of freedom as compared to highlights mounted in a fixed positionand orientation relative to the chassis of the vehicle.

In contrast, example embodiments include a digital micromirror device(“DMD”) and controllable light sources for steering a light beamindependently of the orientation of the headlight assembly including theDMD. For example, the light beam can be steered in response to anindication of a degree of rotation of a vehicle steering wheel.Independently steerable individual micromirrors can be dynamicallyoriented in response to rotation of the steering wheel. Further, thebrightness (e.g., luminance) of controllable light sources forilluminating the DMD can be individually controlled (e.g., adjusted), sopower can be conserved by reducing the brightness of the light beam fora selected azimuth.

In example embodiments, individually controlled lamps are arranged toselectively illuminate partially overlapping portions of an opticallyactive portion of a DMD (e.g., in quasi-sparse illumination). Inquasi-sparse illumination, portions of scenes illuminated by lightreflected from the DMD are selectively more brightly illuminated thanother portions (e.g., by focusing of light from different lightsources). Accordingly, the partial overlap can be determined in thespatial domain and the angular domain. For example, the individuallycontrolled light sources can be independently controlled by regulating(e.g., on, off, or various levels there between) the power applied tocorresponding light sources. Accordingly, independently controlling arespective light source can save power (and reduce heat dissipation) byreducing illumination to a specific DMD area (e.g., which wouldotherwise be projected to non-road surface area).

In example embodiments, the micromirrors can be rapidly switched ON orOFF to shape the beam of light in response to one or more indications ofdriving conditions. For example, the indications can be separately orcollectively generated by a predictive algorithm based on globalpositioning system (GPS) data and information from sensors in a vehicle(such as LiDAR, radar, cameras and inter-vehicle safety systems). Theheadlight beam shaping can include applications such as steering aheadlight beam downwards to deliver higher peak luminance to a roadsurface when an on-coming vehicle is detected, mapping a predictedvehicle path to deliver higher peak luminance following ayet-to-be-driven-upon road curve and averting the headlight beam from anillumination pattern likely to “blind” the vision of the operator of anon-coming vehicle. The beam steering with mutually independentlymodulated light sources (e.g., for selective multi-axial beam steering)can conserve power and increase safety for the vehicle, the on-comingvehicles, pedestrians and other beings or objects.

In example embodiments, one or more of the individually controlled lightsources is/are arranged to emit light for projecting towards a concavemirror for reflectively illuminating selected portions of a DMD. Forexample, one or more of the individually controlled lamps illuminate(s)different but overlapping portions of the concave mirror, so different(but generally overlapping) optically active portions of the DMD areilluminated. Such arrangements facilitate a compact arrangement ofcomponents because the individually controlled lamps can be arranged tobe closer to the DMD. The compact arrangement can be used to reducecost, complexity and space requirements of a headlight assembly.

FIG. 1 is an orthographic view of a headlight assembly for beam steeringwith quasi-sparse illumination. The headlight assembly 100 generallyincludes a headlight assembly casing 110 (including lens casing 112),light sources 120, 122 and 124, light source lenses 130, 132 and 134, aDMD 140 (affixed to package/substrate 142), a concave mirror 150, anoptional asymmetric aperture 160 and a projection lens (170 and 180)including for focusing collimated light for projection with respect toan axis 190 (e.g., centered or biased to the left or right and/orupwards or downward of axis 190 as shown in FIG. 1).

The light sources 120, 122 and 124 can be mutually independentlycontrollable lamps such as incandescent light bulbs, halogen or xenonlamps, light-emitting diode (LED) arrays and/or laser diodes (e.g., forexciting a phosphor surface for emission of light of a selectedfrequency). The light sources 120, 122 and 124 can be formed in separatesubstrates or the same substrate in which various light-emittingportions thereof can be individually and selectively controlled. Thelight sources 120, 122 and 124 are usually the same color (e.g., whitefor highway headlight applications), but some applications can includelamps of mutually different colors and/or color temperatures foradditive (or subtractive) color synthesis in varying applications. Whilethree light sources are described, various embodiments include as manyas 100 or more independently controlled light sources for achievingfiner source modulation for more finely controlled beam steering.

The light sources 120, 122 and 124 are arranged to produce light fordirectional focusing by light source lenses 130, 132 and 134. Each ofthe light source lenses 130, 132 and 134 includes a concave surface forrefracting incident light from a respective one of the light sources120, 122 and 124 into generally parallel (e.g., collimated) light raysdirected: (a) towards the DMD 140 directly; or (b) as shown in FIGS. 2Aand 2B, towards the DMD 140 via the concave mirror 150.

The concave mirror 150 is usually a complex geometric shape (e.g., aninterior biconic surface) including a reflective surface curved (e.g.,folded) inwards, so incident light is reflected into converging rays forcollection on the optically active surface of the DMD 140. The shape ofthe mirror is arranged for focusing light from each of the light sources120, 122 and 124. Each light source is associated with (e.g., arrangedto illuminate) a respective set of micromirrors. Because the respectivesets of micromirrors are partially overlapping, a respective set canshare some micromirrors with another one of the respective sets.

The shape of the mirror and the arrangement of the light sources 120,122 and 124 are arranged to generally illuminate the whole of theoptically active surface of the DMD 140, or to more brightly illuminatespecific portions (such as a center-to-left portion or a center-to-rightportion) of the optically active surface of the DMD 140 (e.g., see FIG.3). The relative degrees of illumination of the portions opticallyactive surface of the DMD 140 can be controlled by individuallycontrolling the amount of light (e.g., luminance) generated by each ofthe light sources 120, 122 and 124. The light from selected lightsources 120, 122 and 124 are optically coupled to illumination opticsfor generating partially overlapping beam profiles in the spatial andangular domains. The partially overlapping beam profiles create asparsely filled (e.g., sparsely illuminated) pupil, so light reflectedfrom selected portions of the optically active surface of the DMD 140illuminates portions of a scene based on a selected azimuth (e.g.,selected by a predictive azimuth). The partially overlapping beamprofiles also generate a brightness greater than a brightness generatedby a single light source.

In an embodiment, the DMD 140 includes a bi-dimensional array ofreflective elements (e.g., micromirrors) arranged in rows and columns,where each such reflective element controls illumination with respect toa “pixel” (e.g., a micromirror for individually controlling a particularportion of the focused light beam for projection). The reflectiveelements selectively control the angle and location at which the focusedlight beam encounters the back (e.g., DMD-side) surface of theprojection lens 180.

The reflective elements of the DMD 140 are individually responsive to aprocessor (e.g., see FIG. 11) for optically steering the projected beam.The projected beam can also be steered by individually controlling thedegree of brightness of the individual light sources 120, 122 and 124.Accordingly, the projected beam can be steered by individuallycontrolling the degree of brightness of the individual light sources120, 122 and 124 and/or controlling individual micromirrors(collectively or individually). When the brightness of an individuallight source 120, 122 and 124 is adjusted (e.g., reduced), power isconserved.

In embodiments including one-axis micromirrors, each pixel can besteered left and right, so the beam from a particular micromirror can beentirely directed away from the projection optics (e.g., projection lens180 and into a light trap, so the beam from the particular micromirroris not projected) or to a selected location on the projection lens 180(e.g., so the beam from the particular micromirror can be projected tothe left, the center or the left of the axis of projection 190).

The pixel rays reflected by the DMD 140 are internally projected throughan optional asymmetric aperture 160 for controlling the brightness andthe contrast ratio of the total projected light. Generally, withnarrowed apertures, the contrast ratio of illuminated subjects isincreased and the overall brightness is decreased. With wider apertures,the contrast ratio is decreased and the overall brightness is increased(e.g., see FIG. 4).

The pixel rays reflected by the DMD 140 are projected cone can besteered horizontally or vertically with respect to the axis ofprojection 190 (e.g., without repositioning or reorienting any lenses).The projected of pixel rays reflected by the DMD 140 can be projected inresponse to various combinations of driving conditions, predictivealgorithms and mutually independent modulation of light sources inconjunction with DMD modulation of mirrors (e.g., for pedestrianmasking).

Example embodiments of the headlight assembly 100 are describedhereinbelow in connection with a top-view section (FIG. 2A) and aside-view section (FIG. 2B).

FIG. 2A is a top view of a headlight assembly for beam steering withquasi-sparse illumination. The headlight assembly 200 is a headlightassembly such as the headlight assembly 100 and generally includes theheadlight light sources 120, 122 and 124, a light source lenses 130, 132and 134, a DMD 140 (affixed to substrate 142), a concave mirror 150, anoptional asymmetric aperture 160, a and a projection lens 170 and 180for focusing collimated light for projection with respect to an axis 190(e.g., centered or biased to the left or right and/or upwards ordownward of axis 190 as shown in FIG. 1).

As described hereinabove, the light source 120, 122 and 124 are lampsthat are source-modulated independently of one another. The lightsources 120, 122 and 124 are arranged to produce light for directionalfocusing by light source lenses 130, 132 and 134 towards the DMD 140 viathe biconic mirror 150. As described hereinbelow in connection with FIG.3, the light sources 120, 122 and 124 are arranged to produce light (inconjunction with the operation of concave mirror 150), so the DMD isgenerally uniformly illuminated with partially overlapping beam patternsfrom the respective light sources. In the example of FIG. 2A, thecontribution to steering the projected beam by source-modulating thelight sources 120, 122 and 124 (independently of one another) isrelatively minimal as the projected light beam (as shown in crosssection exiting the projection lens 180) is centered about the axis ofprojection 190.

FIG. 2B is a side view of a headlight assembly for beam steering withquasi-sparse illumination. The headlight assembly 200 is a headlightassembly such as the headlight assembly 100 and generally includes thelight sources 120, 122 and 124, a light source lenses 130, 132 and 134,a DMD 140 (affixed to substrate 142), a concave mirror 150, an optionalasymmetric aperture 160, a projection lens 170 and 180 for focusingcollimated light for projection with respect to an axis 190.

As described hereinabove, each pixel ray of the DMD 140 can be steeredleft and right or up and down, so the beam from a particular micromirrorcan be entirely directed away from the projection lens 180 or to aselected location on the projection lens 190. For example, a “digital”DMD mirror can be in one of the two states ON (+12 degrees) and OFF (−12degrees): accordingly, beams can be steered along a left-right axis oran up-down axis depending upon the orientation of the DMD device.

FIG. 3 is a group of graphs showing irradiance plots of DMD opticallyactive surfaces for source-modulated beam steering with quasi-sparseillumination. For example, the surface of a DMD (such as DMD 140)includes illuminated surfaces 310, 320 and 330, which show contributionsof the respective light sources (e.g., 120, 122 and 124) to illuminatethose surfaces 310, 320 and 330. Left, center and right graphs 300include a respective azimuth for indicating a center-point (e.g.,one-dimensional center-point) of irradiance contributed by therespective light source.

In an embodiment, the DMD can be a large-scale DMD, so multiple whiteLEDs can be arranged to provide sufficient etendue for a targetapplication, such as the brightness required by vehicle headlights onpublic roads. The DMD includes an aspect ratio of 2:1, which facilitatesa side-by-side arrangement of LEDs to provide sufficient illumination(etendue) for achieving a high peak illuminance at an acceptable fieldof view for projection as a headlight beam.

In an embodiment, a quasi-sparse illumination architecture includescontribution of partially overlapping light beam from separatelycontrollable LEDs for generating a high peak luminance near the centerof the DMD. Quasi-sparse illumination-based beam steering can beachieved by changing each partially overlapped beam's contribution bychanging a respective input current to an individual LED. Accordingly:the average power consumption can be reduced by over 20 percent whendriving in diverse road conditions; the thermal load in the headlightassembly can be reduced; the LED life-time can be increased (andreliability increased); and yellowing artifacts at the edge of the fieldof view of the beam can be reduced.

Quasi-sparse illumination-based beam steering can be achieved bychanging contribution of left, center and right partially overlappedbeams by changing a respective input current to an individual LED. Forexample, illuminated surface 310 includes an illuminated spot centeredunder azimuth 312. Curve 314 shows the degree of illumination of ahorizontal line in the center of the illuminated surfaces 310 extendingfrom left to right. The azimuth 312 is associated with a center point onthe curve 314 at which the area under the curve 314 to the left of thecenter point is equal to the area under the curve 314 to the right ofthe center point.

The illuminated surface 320 includes an illuminated spot centered underazimuth 322. Curve 324 shows the degree of illumination of a horizontalline in the center of the illuminated surfaces 320 extending from leftto right. The azimuth 322 is associated with a center point on the curve324 at which the area under the curve 324 to the left of the centerpoint is equal to the area under the curve 324 to the right of thecenter point.

The illuminated surface 320 includes an illuminated spot centered underazimuth 322. Curve 324 shows the degree of illumination of a horizontalline in the center of the illuminated surfaces 320 extending from leftto right. The azimuth 322 is associated with a center point on the curve324 at which the area under the curve 324 to the left of the centerpoint is equal to the area under the curve 324 to the right of thecenter point

The illuminated surface 330 includes an illuminated spot centered underazimuth 332. Curve 334 shows the degree of illumination of a horizontalline in the center of the illuminated surfaces 330 extending from leftto right. The azimuth 332 is associated with a center point on the curve334 at which the area under the curve 334 to the left of the centerpoint is equal to the area under the curve 334 to the right of thecenter point.

Accordingly, activating the left, center and right LEDs uniformlyilluminates the DMD, activating the left and center LEDs illuminates theleft and center portions of the DMD, and activating the center and rightLEDs illuminates the center and right portions of the DMD. The projectedbeam is steered in accordance with the illuminated portions of the DMD.

FIG. 4A is a diagram of an inner margin of a first projection aperture.The projection aperture 400 is similar to aperture 160 and is generallycircular and is narrowed along one side. For example, the aperture shapecan be narrowed by drawing a chord through two points of the circle, andfolding an arc (e.g., the smaller arc) defined by the chord inwards.With a narrowed aperture, the contrast ratio is increased and theoverall brightness is decreased. The asymmetric inner margin of theaperture 400 masks an outward portion of the cone (or pyramid) of thefocused light along the projection axis, so the contrast of objectsilluminated by the partially masked beam is increased (e.g., which canincrease the likelihood that a driver would more quickly notice andidentify the illuminated objects).

FIG. 4B is a diagram of an inner margin of a second projection aperture.The projection aperture 402 is similar to aperture 160 and is generallycircular and is narrowed on opposing sides. For example, the apertureshape can be narrowed by drawing a chord through two points on a firstside of the circle, and folding an arc (e.g., the smaller arc) definedby the chord inwards. The aperture shape can be further narrowed bydrawing a second chord through two points on an opposite side of thecircle, and folding an arc (e.g., the smaller arc) defined by the chordinwards. The doubly asymmetric inner margin of the aperture 402 masks anoutward portion of the cone of the focused light along the projectionaxis, so the contrast of objects illuminated by the partially maskedbeam is increased (e.g., more than the contrast ratio of the aperture400).

FIG. 4C is a diagram of an inner margin of an illumination aperture. Theprojection aperture 404 is for masking light from light sources (e.g.,120, 122 and 124) and for shaping the contours of incident lightimpinging the DMD. Accordingly, the projection aperture 404 is arrangedin a convenient location in the light path between the light sources(e.g., 120, 122 and 124) and the DMD.

For example, the aperture 404 shape (e.g., the outline of inner margin)can be defined as the outer boundaries of three circles of which twocircles overlap a center circle. In an embodiment, the center of eachcircle is collinear (e.g., in a straight line) with the centers of theoverlapping circles forming the inner margin of the aperture 404. In anembodiment, a circle for defining the aperture 404 inner margin isdefined in accordance with a relative position of a corresponding lightsource circle (e.g., two, three, four, five or more circles) to definethe shape of the inner margin of the projection aperture 404.

The asymmetric inner margin of the aperture 404 masks an outward portionof the cone of the focused light. Masking the outward portion of thecone of the light focused on the DMD increases the contrast ratio of theprojected beam. The outline of the masked cone of the light illuminatingthe DMD approximates the aspect ratio and the outline of the opticallyactive surface of the DMD.

FIG. 4D is a diagram of an illumination and/or projection aperture. Whenarranged as an illumination aperture, the aperture 404 can be located ina convenient location in the light path between the light sources (e.g.,120, 122 and 124) and the DMD 140 (e.g., where the aperture 406 a is formasking the light source 120, the aperture 406 b is for masking thelight source 122, and the aperture 406 c is for masking the light source124). When arranged as a projection aperture, the aperture 404 can belocated in a convenient location in the light path between the DMD andthe projection lens 170 and 180 elements.

For example, the aperture 406 shape (e.g., the outline of inner margins)can be defined as the outer boundaries of three non-overlappingellipses. In an embodiment, the center of each ellipse is collinear(e.g., in a straight line) with the short axes of each of the threeellipses of the aperture 406. In an embodiment, a circle for definingthe aperture 406 inner margins is defined in accordance with a relativeposition of a corresponding light source ellipse (e.g., two, three,four, five or more ellipses) to define the shape of the inner margin ofthe aperture 404.

The asymmetric inner margin of the aperture 406 masks portions of thecone of the focused light. Masking the portions of the cone of the lightfocused on the DMD increases the contrast ratio of the projected beam.The outline of the masked cone of the light illuminating the DMDapproximates the aspect ratio and the outline of the optically activesurface of the DMD.

FIG. 5A is a diagram of a system for illuminating a DMD withnon-overlapping beam generation from multiple light sources. Forexample, system 501 includes multiple light sources 511, 512 and 513,lenses 514, 517 and 518, and a DMD 540 aligned in accordance with anaxis 519 extending from the middle light source 512 to the center pointon the optically active surface of the DMD 540.

In operation, the multiple light sources 511, 512 and 513 (right, centerand left, respectively) are arranged to generate light for illuminatingthe optically active surface of the DMD 540. The lenses 514, 517 and 518are aligned along the axis 519 and are arranged to focus the lightsourced by the multiple light sources 511, 512 and 513 on the opticallyactive surface of the DMD 540. The light incident on the opticallyactive surface of the DMD 540 can be uniformly or non-uniformlydistributed. When the DMD 540 is uniformly distributed, light sourcedfrom different light sources does not substantially overlap (e.g., bymore than a few pixels) on the optically active surface of the DMD 540.When the DMD 540 is non-uniformly distributed, light from differentlight sources can be partially overlapped. Accordingly, the system 501can be beam steered by source-modulating either of light source 511 orlight source 513 when the DMD 540 is non-uniformly illuminated.

FIG. 5B is a diagram of a system for illuminating a DMD with partiallyoverlapping beam generation from multiple light sources. For example,system 502 includes multiple light sources 521, 522 and 523, lenses 524,525, 526, 527 and 528, and a DMD 540 aligned in accordance with an axis529 extending from the middle light source 522 to the center point onthe optically active surface of the DMD 540.

In operation, the light sources 521, 522 and 523 (right, center andleft, respectively) are arranged to generate light for illuminating theoptically active surface of the DMD 540. The lenses 524, 525 and 526 arearranged to focus light from respective light sources 521, 522 and 523upon lens 527. Lenses 527 and 528 are aligned along the axis 529 and arearranged to focus the light sourced by the multiple light sources 521,522 and 523 on the optically active surface of the DMD 540. The lightincident on the optically active surface of the DMD 540 is uniformlydistributed, but light sourced from different light sources partiallyoverlaps (e.g., by more than a few pixels) on the optically activesurface of the DMD 540. The system 501 can source-modulated beam steeredby source-modulating either of light source 521 or light source 523.

FIG. 5C is a diagram of a system for illuminating a DMD with completelyoverlapping beam generation from multiple light sources. For example,system 503 includes multiple light sources 531, 532 and 533, lenses 534,535, 536, 537 and 538, and a DMD 540 aligned in accordance with an axis539 extending from the middle light source 532 to the center point onthe optically active surface of the DMD 540.

In operation, the multiple light sources 531, 532 and 533 (right, centerand left, respectively) are arranged to generate light for illuminatingthe optically active surface of the DMD 540. The lenses 534, 535 and 536are arranged to focus light from light sources 531, 532 and 533,respectively, upon lens 537. Lenses 537 and 538 are aligned along theaxis 539 and are arranged to focus the light sourced by the multiplelight sources 531, 532 and 533 on the optically active surface of theDMD 540. The light incident on the optically active surface of the DMD540 is uniformly distributed, but light sourced from different lightsources completely overlaps on the optically active surface of the DMD540. The system 501 can dim the incident light by source-modulating anycombination of the light sources 531, 532 and 533.

FIG. 6 is a side view of a headlight assembly for source-modulated beamsteering with quasi-sparse illumination from same-side light sources.The headlight assembly 600 generally includes the headlight lightsources 620, 622 and 624, a light source lenses 630, 632 and 634, a DMD640 (affixed to substrate 642), a concave mirror 650, an optionalasymmetric aperture 660, a collimating lens 670 and a projection lens680 for focusing collimated light for projection with respect to an axis690 (e.g., centered or biased to the left or right and/or upwards ordownward of axis 690 as shown in FIG. 1).

As described hereinabove, the light sources 620, 622 and 624 are lampsthat are source-modulated independently of one another. The lightsources 620, 622 and 624 are arranged to produce light for directionalfocusing by light source lenses 630, 632 and 634 towards the DMD 640 viathe concave mirror 650 (e.g., a biconic mirror for producing asymmetricF-numbers). The light sources 620, 622 and 624 are arranged to producelight (in conjunction with the operation of concave mirror 650), so theDMD is generally uniformly illuminated with partially overlapping beampatterns from the respective light sources. In the example of FIG. 6,the projected beam can be steered by source-modulating the light sources620 and 624 (independently of one another) and by spatial lightmodulation using the micromirrors of the DMD 640. The projected lightbeam (as shown in cross section exiting the projection lens 680) iscentered to the right of the axis of projection 690.

The headlight light sources 620, 622 and 624 the light source lenses630, 632 and 634 are arranged below (e.g., subjacent to) the DMD 640 (asmounted on substrate 642) and on the same side as the concave mirror650, where the concave mirror is arranged above the DMD 640 forilluminating (e.g., directly illuminating) the optically active surfaceof the DMD 640.

FIG. 7 is a diagram of multiple collection lenses for independentlysituated and oriented light sources, for partially overlapping beamgeneration for illuminating a DMD. For example, system 700 includesmultiple light sources 720, 722 and 724, collection lenses 730, 732 and734 and a DMD 740 aligned in accordance with an axis 792 extending fromthe middle light source 722, through the center of the collection lens732 and to the center point on the optically active surface of the DMD740. Each of the light sources 720, 722 and 724 can be shifted laterally(e.g., parallel to the plane of the DMD 740) and tilted (e.g., gimbaled)to point towards the DMD 740. Accordingly, each of the light sources720, 722 and 724 is tilted, so an axis of projection for each lightsource points towards the micromirrors of the DMD. The light sources720, 722 and 724 are arranged to respectively illuminate the opticalsurface of the DMD 740 with partially overlapping beams (e.g., asdescribed hereinabove in connection with FIG. 3).

In operation, the multiple light sources 720, 722 and 724 (right, centerand left, respectively) are arranged to generate source-modulated lightfor illuminating the optically active surface of the DMD 740. Thecollection lenses 730, 732 and 734 are arranged to focus light fromlight sources 720, 722 and 724, respectively, upon the optically activesurface of the DMD 740: the beams of light refracted by collectionlenses 734 and 732 partially overlap when illuminating a left-to-centerportion of the optically active surface of the DMD 740 and the beams oflight refracted by collection lenses 732 and 730 partially overlap whenilluminating a center-to-right portion of the optically active surfaceof the DMD 740. Accordingly, the system 700 is arranged toelectronically steer an optical beam responsive to the source modulation(e.g., of light source 720 or 724) and/or controlling micromirrors ofthe DMD 740.

FIG. 8 is a diagram of a single collection lens for independentlysituated and oriented light sources, for partially overlapping beamgeneration for illuminating a DMD. For example, system 800 includesmultiple light sources 820, 822 and 824, a collection lens 830 and a DMD840 aligned in accordance with an axis 892 extending from the middlelight source 822, through the center of the collection lens 830 and tothe center point on the optically active surface of the DMD 840. Each ofthe light sources 820, 822 and 824 can be shifted laterally (e.g.,parallel to the plane of the DMD 840) and tilted (e.g., gimbaled), so anaxis of projection for each light source points towards the DMD 840.

The light sources 820, 822 and 824 are arranged to respectivelyilluminate the optical surface of the DMD 840 with partially overlappingbeams (e.g., as described hereinabove in connection with FIG. 3) aslensed by the collection lens 830. The collection lens 830 is a singlebeam-forming lens for combining (e.g., focusing) beams on the opticallyactive surface of the DMD 840. The collection lens 830 can be biconic orradially symmetrical.

In operation, the multiple light sources 820, 822 and 824 (right, centerand left, respectively) are arranged to generate source-modulated lightfor illuminating the optically active surface of the DMD 840. Thecollection lenses 830, 832 and 834 are arranged to focus light fromlight sources 820, 822 and 824, respectively, upon the optically activesurface of the DMD 840: the beams of light sourced by the light sources824 and 822 partially overlap when illuminating a left-to-center portionof the optically active surface of the DMD 840 and the beams of lightsourced by the light sources 822 and 820 partially overlap whenilluminating a center-to-right portion of the optically active surfaceof the DMD 840. Accordingly, the system 800 is arranged toelectronically steer an optical beam responsive to the source modulation(e.g., of light source 820 or 824) and/or controlling micromirrors ofthe DMD 840.

FIG. 9 is a diagram of a single collection lens for planar lightsources, for partially overlapping beam generation for illuminating aDMD. For example, system 900 includes multiple light sources 920, 922and 924, a collection lens 930, and a DMD 940 aligned in accordance withan axis 992 extending from the middle light source 922, through thecenter of the collection lens 930 and to the center point on theoptically active surface of the DMD 940.

The light sources 920, 922 and 924 are arranged in a plane (e.g.,parallel to the plane of the DMD 940) for respectively illuminating theoptical surface of the DMD 940 with partially overlapping beams (e.g.,as described hereinabove in connection with FIG. 3) as lensed by thecollection lens 930. The planar arrangement of the light sources 920,922 and 924 (e.g., same planar arrangement) achieves simpler mechanicallayouts and thermal management. The collection lens 930 is a singlebeam-forming lens for combining beams on the optically active surface ofthe DMD 940. The collection lens 930 can be biconic or radiallysymmetrical.

In operation, the multiple light sources 920, 922 and 924 (right, centerand left, respectively) are arranged to generate source-modulated lightfor illuminating the optically active surface of the DMD 940. Thecollection lenses 930, 932 and 934 are arranged to focus light fromlight sources 920, 922 and 924, respectively, upon the optically activesurface of the DMD 940: the beams of light sourced by the light sources924 and 922 partially overlap when illuminating a left-to-center portionof the optically active surface of the DMD 940 and the beams of lightsourced by the light sources 922 and 920 partially overlap whenilluminating a center-to-right portion of the optically active surfaceof the DMD 940. Accordingly, the system 900 is arranged toelectronically steer an optical beam responsive to the source modulation(e.g., of light source 920 or 924) and/or controlling micromirrors ofthe DMD 940.

FIG. 10 is a side view of a headlight assembly for beam steering withquasi-sparse illumination from direct and indirect light sources. Theheadlight assembly 1000 generally includes the headlight light sources1020, 1022 and 1024, light source lenses 1030, 1032 and 1034, a DMD1040, a concave mirror 1050 and a collimating projection lens 1070 forfocusing collimated light for projection with respect to an axis 1090(e.g., centered or biased to the left or right and/or upwards ordownward of axis 1090).

As described hereinabove, the light source 1020, 1022 and 1024 are lampsthat are source-modulated independently of one another. The lightsources 1022 and 1024 are arranged to produce light for directionalfocusing by light source lenses 1032 and 1034 along a first DMDillumination path indirectly towards the DMD 1040 via the concave mirror1050 (e.g., biconic mirror for producing asymmetric F-numbers). Thelight source 1020 is arranged to produce a light beam for directionalfocusing by light source lens 1030 along a second DMD illumination pathdirectly towards the DMD 1040. The light sources 1020, 1022 and 1024 arearranged to produce light beams, so the DMD is generally uniformlyilluminated with partially overlapping beam patterns from the respectivelight sources.

In the example of FIG. 10, the DMD and (optionally) the light sourcescan be duty cycled by source-modulating the light sources 1020 and 1024(independently of one another) and by cyclically (e.g., at a rate higherthan a rate in which the transitions can be noticed by the human eye)tilting the micromirrors of the DMD 1040 back and forth between firstand second mirror positions. For example, light from a first lightsource (e.g., 1020) can be steered into the projection lens when the DMDmirrors are tilted to −12 degrees (tilted down) and steered away fromthe projection lens when the DMD mirrors are tilted to +12 degrees(tilted up). For a second light source, light from light sources 1022and/or 1024 can be steered into the projection lens when the DMD mirrorsare tilted to +12 degrees (tilted up) and steered away from theprojection lens when the DMD mirrors are tilted to −12 degrees (tilteddown). The projected light beam (as shown in cross section exiting thecollimating projection lens 1070) is centered to the right of the axisof projection 1090. Moreover, duty-cycling of both the light sources andthe DMD mirrors increases reliability and lifetimes of both the lightsources and the DMD. The frequency of duty-cycling the DMD mirrors andlight sources can be selected to avoid perception of flickering, basedon the persistence of vision of the human eye.

The outside (left and right) light sources 1022 and 1024 are arranged toindirectly face the DMD 1040 (along a first DMD illumination path),whereas the center light source 1020 is arranged to directly face theDMD 1040 (along a second DMD illumination path). Such an arrangementmaintains symmetry for beam steering and helps a smaller optical engineheight (e.g., headlight assembly) to be achieved.

Accordingly, illumination architectures are described in which acurved/flat mirror and multiple light sources are located on theopposite ends of DMD. For example, the mirror can be located at the topof the DMD and the multiple light sources located at the bottom of theDMD for a bottom-illuminated device. In another example, For example,the mirror can be located at the right (or left) of the DMD and themultiple light sources located at the left (or right) of the DMD for aside-illuminated device.

FIG. 11 is a block diagram of a vehicle system for source-modulated beamsteering. For example, the vehicle system 1100 includes inputelectronics 1110, system electronics 1120, driver electronics 1130,optical systems 1140 and a beam-steering vehicle 1160. The inputelectronics 1110 can include an ADAS (advanced drivers assistancesystem) 1112 suite for sensor-assisted safety augmentation when drivingthe beam-steering vehicle 1160. The ADAS system is coupled of varioussensors 1114 for electronically and/or optically sensing the position ofsurrounding objects. Examples of the various sensors 1114 include one ormore cameras, one or more radars or LIDARs (light detection andranging), and one or more proximity detectors. Outputs of the varioussensors 1114 are processed to generate an electronic representation ofthe environment surrounding the beam-steering vehicle 1160. For example,a video image from a camera sensor 1114 can be processed by imageprocessing 1116 to determine the presence of pedestrians.

The system electronics 1120 are coupled to receive indications of theelectronic representation of the environment surrounding thebeam-steering vehicle 1160. The system electronics 1120 is arranged tocontrol the driver electronics 1130. For example, the system electronicscan map pixels associated with a pedestrian and ensure that a projectedheadlight beam illuminates areas around the pedestrian (but not thepedestrian itself, so the pedestrian is shielded against theillumination's potentially blinding effects).

The driver electronics 1130 contain power management 1132 circuitry forselectively applying power to system components in response to operatorcontrols (e.g., 1162 and/or 1164) or in response to an electronicrepresentation of the environment surrounding the beam-steering vehicle1160. For example, the power management 1132 circuitry is arranged tosource-modulate the illumination sources 1142 for source-modulated beamsteering. The DMD interface 1136 is responsive to the system electronicsand operator controls such as the steering wheel 1162 and turn signalcontrols 1164 to determine the orientation of micromirrors for the DMD1150. The DMD controller 1134 is responsive to the power managementcircuitry 1132 and the DMD interface 1136 to selectively activate themicromirrors of the DMD 1150. For example, the DMD controller 1134 canselectively activate the micromirrors for purposes such as thepedestrian masking and beam steering.

The optical systems 1140 includes illumination sources 1142 (such asLED, lasers and incandescent lamps). Illumination sources 1142 areresponsive to the power management 1132 circuitry for source-modulatedbeam steering in response to a vehicle turning command (e.g., operatorcontrol of the steering wheel 1162 and/or operation of turn signalcontrols 164). For example, the power management 1132 circuitry reducescurrent to the left and center LEDs during a right turn (e.g., where theleft LED can be fully off, and the center LED can be partially off).Similarly, during a left turn, the system reduces current to the rightand center LEDs (e.g., where the right LED can be fully off and thecenter LED can be partially off). Accordingly, the system performs beamsteering (e.g., beam shaping) by modulating the light source, inaddition to the DMD mirror-based modulation. The reduction of currentfrom modulating the light sources under diverse driving conditionsreduces the power consumption of the driver electronics 1130.

The partial overlap of adjacent pairs of beams from adjacent lightsources (source-modulated independently of one another) can be used inaccordance with multiple purposes. For example, beams from thosedifferent light sources are partially overlapped to provide higher peakbrightness in the overlapped region and the source-dimmed (e.g., inresponse to changing road conditions) to help reduce the average powerconsumption by the light source. Further, adaptive road illumination canbe achieved by simultaneously tilting DMD micromirrors for spatial lightmodulation and modulating source current of those light sources forlight source dimming. The described adaptive road illumination includesbeam profile steering in response to direction of vehicle turns,brightness adjustment according to vehicle speed, glare reduction forother road users (e.g., in response to optical recognition and/orheadlight detection by an optical sensor), communication with other roadusers (e.g., for conveying position information) and masking (e.g.,dimming the light) and marking (e.g., providing at some illumination)pedestrians, animals and road signs to alert the driver without causingglare.

The illumination sources 1142 are coupled to the illumination optics1144 for focusing incident light on the DMD 1150. The DMD (responsive tothe DMD mirror-based modulation and the source-modulated incident light)reflects the incident light into the projection optics 1146 forprojection. The optical systems 1142 (and the DMD 1150) are usuallyincluded in a headlight assembly 1166, where a front-right corner of thebeam-steering vehicle 1160 has a first headlight assembly, and afront-left corner of the beam-steering vehicle 1160 has a secondheadlight assembly. The projected headlight beams can be beam-steered asdescribed hereinbelow.

FIG. 12A is a view (from a vehicle) of beam-steering when the vehicle isdriving straight ahead. For example, scenario 1201 shows the axis of avehicle 1210, which is perpendicular to the front of the vehicle (andpoints directly ahead of the vehicle at all times). When the vehicle istraveling directly forward (e.g., straight ahead) the beam-direction (ofa beam-steering capable beam) is parallel to the axis of the vehicle1210.

FIG. 12B is a view (from a vehicle) of beam-steering when the vehicle ismaking a shallow turn. For example, scenario 1202 shows the axis of avehicle 1210, which is perpendicular to the front of the car. When thevehicle is in the shallow turn to the left, the beam-direction (of abeam-steering capable beam) is steered to the left of the axis of thevehicle 1210. As the vehicle is in the shallow turn to the left,pedestrians 1230 on a street corner are detected by a camera sensor andthe image processed to determine the relative location of thepedestrians 1230 to the beam projected along the beam direction 1220.When the relative location of the pedestrians 1230 is in the path of thebeam (such that the pedestrians 1230 would otherwise be illuminated bythe beam), the pixel rays intersecting the relative location of thepedestrians 1230 are masked (e.g., by reducing the illumination fully orpartially by controlling DMD micromirrors associated with the maskedpixels).

FIG. 12C is a view (from a vehicle) of beam-steering when the vehicle ismaking a sharper turn. For example, scenario 1203 shows the axis of avehicle 1210, which is perpendicular to the front of the car. When thevehicle is in the sharper turn to the left (e.g., having a turn radiusless than the turn radius of the shallow turn in scenario 1202), thebeam-direction is steered more sharply to the left of the axis of thevehicle 1210. As the vehicle is in the sharper turn to the left, thepedestrians 1230 are pedestrian masked 1240 from illumination on astreet corner are detected by a camera sensor and image processing.

In at least one example, a first light source can be optionally dimmedin response to an indication of a driving condition, so power isconserved, and a projected beam can be effectively steered away from alocation associated with the indicated driving condition

Modifications are possible in the described embodiments, and otherembodiments are possible, within the scope of the claims.

What is claimed is:
 1. Apparatus, comprising: a digital micromirrordevice (DMD) including first and second sets of micromirrors, the DMDhaving a DMD input, and the DMD configured to modulate the first andsecond sets of micromirrors responsive to a DMD control signal at theDMD input; a first light source optically coupled to the first set ofmicromirrors, the first light source having a first control input, andthe first light source configured to generate a first modulated beamprofile having a first power and a first brightness for illuminating thefirst set of micromirrors, responsive to a first control signal at thefirst control input; a second light source optically coupled to thesecond set of micromirrors, the second light source having a secondcontrol input, and the second light source configured to generate asecond modulated beam profile having a second power and a secondbrightness for illuminating the second set of micromirrors and at leastsome of the first set of micromirrors, responsive to a second controlsignal at the second control input; input electronics having a drivingcondition output, the input electronics configured to: obtain a drivingcondition; and output an indication of the driving condition at thedriving condition output; power management circuitry having a powermanagement input and first and second illumination outputs, the powermanagement input adapted to be coupled to a vehicle, the firstillumination output coupled to the first control input, the secondillumination output coupled to the second control input, and the powermanagement circuitry configured to: receive at least one of a vehiclecontrol signal from the vehicle or the indication of the drivingcondition from the input electronics; provide the first control signalat the first illumination output, and adjust the first control signalresponsive to at least one of the vehicle control signal or theindication of the driving condition; and provide the second controlsignal at the second illumination output; and a DMD controller having acontroller input and a controller output, the controller input coupledto the driving condition output, the controller output coupled to theDMD input, and the DMD controller configured to provide the DMD controlsignal at the controller output, and adjust the DMD control signalresponsive to at least one of the indication of the driving condition orthe vehicle control signal.
 2. The apparatus of claim 1, the DMD furtherincluding a third set of micromirrors, the power management circuitryhaving a third illumination output, the power management circuitryfurther configured to provide a third illumination signal at the thirdillumination output, and adjust a third control signal responsive to thedriving condition output, the apparatus further comprising a third lightsource optically coupled to a third set of micromirrors, the third lightsource having a third control input, and the third light sourceconfigured to generate a third modulated beam profile having a thirdpower and a third brightness for illuminating the third set ofmicromirrors and at least some of the second set of micromirrors,responsive to the third control signal at the third control input. 3.The apparatus of claim 2, wherein the vehicle control signal is a leftor right turn and the driving condition is a left or right turn.
 4. Theapparatus of claim 2, wherein a projection pupil formed by projectionoptics for collecting reflected light from the first and second sets ofmicromirrors is sparsely filled by the first, second, and thirdmodulated beam profiles, and wherein an etendue of the DMD is sparselyfilled.
 5. The apparatus of claim 2, the DMD further comprising fourth,fifth, and sixth sets of micromirrors, the power management circuitryhaving fourth, fifth, and sixth illumination outputs, the powermanagement circuitry further configured to provide a fourth controlsignal at the fourth illumination output, and adjust the fourth controlsignal responsive to the vehicle control signal; provide a fifth controlsignal at the fifth illumination output, and adjust the fifth controlsignal responsive to the vehicle control signal; and provide a sixthcontrol signal at the sixth illumination output, and adjust the sixthcontrol signal responsive to the vehicle control signal, the apparatusfurther comprising: a fourth light source optically coupled to thefourth set of micromirrors, the fourth light source having a fourthcontrol input, and the fourth light source configured to generate afourth modulated beam profile having a fourth power and a fourthbrightness for illuminating the fourth set of micromirrors, responsiveto the fourth control signal at the fourth control input; a fifth lightsource optically coupled to the fifth set of micromirrors, the fifthlight source having a fifth control input, and the fifth light sourceconfigured to generate a fifth modulated beam profile having a fifthpower and a fifth brightness for illuminating the fifth set ofmicromirrors and at least some of the fourth set of micromirrors,responsive to the fifth control signal at the fifth control input; and asixth light source optically coupled to the sixth set of micromirrors,the sixth light source having a sixth control input, and the sixth lightsource configured to generate a sixth modulated beam profile having asixth power and a sixth brightness for illuminating the sixth set ofmicromirrors and at least some of the fifth set of micromirrors,responsive to the sixth control signal at the sixth control input. 6.The apparatus of claim 3, wherein the first, second, and third lightsources are light-emitting diodes, lasers, or laser-illuminatedphosphors.
 7. The apparatus of claim 2, further comprising a mirrorarranged above an active surface of the DMD, wherein at least one of thefirst, second, and third light sources is arranged below the activesurface of the DMD to irradiate the mirror, and wherein the mirror isarranged to reflect incident light upon at least some of the first,second, and third sets micromirrors.
 8. The apparatus of claim 2,further comprising a first, second, and third set of illuminationoptical elements configured to collimate, beam shape, and focus lightfrom a respective first, second, and third sets of light sources towardsat least some of the first, second, and third sets of micromirrors,wherein the first, second, and third sets of light sources are tilted topoint towards at least some of the first, second, and third sets ofmicromirrors.
 9. The apparatus of claim 2, further comprising a set ofillumination optical elements configured to collimate, beam shape, andfocus light from the first, second, and third light sources towards atleast some of the first, second, and third sets of micromirrors, whereinthe first, second, and third light sources are tilted to point towardsat least some of the first, second, and third sets of micromirrors. 10.The apparatus of claim 2, further comprising a set of illuminationoptical elements configured to collimate, beam shape, and focus lightfrom the first, second, and third light sources towards at least some ofthe first, second, and third sets of micromirrors, wherein the first,second, and third light sources are arranged in a plane parallel to theplane of the DMD to illuminate at least some of the first, second, andthird sets of micromirrors.
 11. A headlight assembly comprising: adigital micromirror device (DMD) including micromirrors; a first lightsource optically coupled to the micromirrors, the first light sourceconfigured to generate a first beam profile illuminating a first portionof the micromirrors; a second light source optically coupled to themicromirrors, the second light source configured to generate a secondbeam profile illuminating a second portion of the micromirrors, thefirst and second beam profiles partially overlapping on themicromirrors; a third light source optically coupled to themicromirrors, the third light source configured to generate a third beamprofile illuminating a third portion of the micromirrors, the second andthird beam profiles partially overlapping on the micromirrors; and amirror optically coupled between the first light source and the DMD, andbetween the third light source and the DMD, the mirror configured toreflect light from the first light source onto the DMD and to reflectlight from the third light source onto the DMD.
 12. The headlightassembly of claim 11, wherein a projection pupil formed by projectionoptics for collecting reflected light from micromirrors is sparselyfilled by the first, second, and third beam profiles, and wherein anetendue of the DMD is sparsely filled.
 13. The headlight assembly ofclaim 12, wherein illumination optical elements are configured topartially overlap beam profiles of adjacent beams.
 14. The headlightassembly of claim 11, wherein light from the first light source issteered into a projection lens in response to a particular one of themicromirrors being in a first mirror position and steered away from theprojection lens in response to the particular one of the micromirrorsbeing in a second mirror position, wherein light from the second lightsource is steered into the projection lens in response to the particularone of the micromirrors being in the second mirror position and steeredaway from the projection lens in response to the particular one of themicromirrors being in the first mirror position, and wherein theparticular one of the micromirrors is duty-cycled to alternate betweenthe first and second mirror positions.
 15. The headlight assembly ofclaim 11, wherein the mirror is a concave mirror, the mirror configuredto reflect incident light in accordance with asymmetric F- (focallength-) numbers.
 16. The headlight assembly of claim 15, wherein themirror is configured to reflect light from the second light source ontothe DMD.
 17. The headlight assembly of claim 11, further comprising asparse aperture configured to partially restrict light incident upon orreflected by the DMD.
 18. The headlight assembly of claim 11, furthercomprising: input electronics configured to sense a sensed drivingcondition; and a processor configured to source-modulate the first lightsource, independently of the second, and third light sources, to adjustpower and brightness in response to the sensed driving condition. 19.The apparatus of claim 1, wherein the driving condition is a steeringwheel position, a turn signal control, the presence of a pedestrian, thepresence of an animal, a road sign, vehicle speed, headlight detection,or a communication from another vehicle.